Lesson 6 Magnetic field induced transport in nanostructures
- Short review of the effects of a magnetic field on an electron in bulk system - Effects of a magnetic field on an electron in 0D, 1D, 2D nanostructures (modification of the density of states!!) - Quantization of the magnetic flux - Quantum Hall effect
A) Effect of a uniform magnetic field on a crystal
Free electrons in y and z. Confined electrons in x (by harmonic potential) Landau Levels
Key consequence: Changing the electrons density of states n 3D n 1D Landau Levels
n 3D n 1D General effect of a magnetic field on the electrons density of states: restriction by 2 dimensions n 2D n 0D B) Low dimensional systems in magnetic fields 2D 0D
C) Density of states of a 2D system in a magnetic field (Towards the quantum Hall effect)
D) The Aharonov-Bohm effect: evidence for the magnetic flux quantization L >>L, B 0 Electrons interference effects
Webb experiment to prove the Aharonov-Bohm effect
E) 2D system in a magnetic field: Landau levels and filling factor
42 2
F) The quantum Hall effect - Classical Hall effect
Quantum Hall effect - Experimental facts and elementary theory of integer quantum Hall effect Low-Dimensional semiconductor (ex. 2DEG)
R xx R xy =R H
R K =h/e 2 von Klitzing constant (quantum of resistance)
n=